Universality Class of the Fragmentation of Plastic Materials

An experimental and theoretical study of the fragmentation of plastic materials is presented. In the experiments polyxymethylen particles of spherical shape were fragmented by impacting them against a hard wall. The experiments revealed a power law distribution of fragment masses similar to heterogeneous brittle materials, however, with a significantly lower exponent. To understand the experimental findings a three dimensional discrete element model is introduced. The model discretizes the sample in terms of randomly sized spheres which are connected by elastic beams. To capture the effect of plasticity a novel type of failure criterion is introduced complemented by a healing mechanism of broken particle contacts under compression. Computer simulations show a good quality agreement with the experimental findings.